Okay, left work today, all is good at first. Booted it a couple times, fuel pressure good (climbed well past 1800 psi), no misfires, runs great up to 4,500-5,000 rpm through 3rd gear and pulls strong.
After a couple of more miles, I get another opening from a stoplight, boot it again, runs fine through first and second, hit third fuel pressure quits rising at just over 1k psi and flutters a bit, engine bogs, then the CEL flashes, but goes back out when I let off and it stays off.
Car drives rest of way home fine since I didn't get on it again.
It definitely seems the issue is fuel pressure related, so does this sound like the low pressure line issue, or could it be with the high pressure pump at the engine?